[PATCH] drm/amdgpu: Fix UVD contiguous CS mapping problem

[Christian König]

Am 11.11.24 um 09:05 schrieb Arunpravin Paneer Selvam:
> When starting the mpv player, Radeon R9 users are observing
> the below error in dmesg.
>
> [drm:amdgpu_uvd_cs_pass2 [amdgpu]]
> *ERROR* msg/fb buffer ff00f7c000-ff00f7e000 out of 256MB segment!
>
> The patch tries to set the TTM_PL_FLAG_CONTIGUOUS for both user
> flag(AMDGPU_GEM_CREATE_VRAM_CONTIGUOUS) set and not set cases.
>
> Closes:https://gitlab.freedesktop.org/drm/amd/-/issues/3599
> Closes:https://gitlab.freedesktop.org/drm/amd/-/issues/3501
> Signed-off-by: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam at amd.com>
> Cc: stable at vger.kernel.org
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c | 18 +++++++++++-------
>   1 file changed, 11 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> index d891ab779ca7..9f73f821054b 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> @@ -1801,13 +1801,17 @@ int amdgpu_cs_find_mapping(struct amdgpu_cs_parser *parser,
>   	if (dma_resv_locking_ctx((*bo)->tbo.base.resv) != &parser->exec.ticket)
>   		return -EINVAL;
>   
> -	(*bo)->flags |= AMDGPU_GEM_CREATE_VRAM_CONTIGUOUS;
> -	amdgpu_bo_placement_from_domain(*bo, (*bo)->allowed_domains);
> -	for (i = 0; i < (*bo)->placement.num_placement; i++)
> -		(*bo)->placements[i].flags |= TTM_PL_FLAG_CONTIGUOUS;
> -	r = ttm_bo_validate(&(*bo)->tbo, &(*bo)->placement, &ctx);
> -	if (r)
> -		return r;
> +	if ((*bo)->flags & AMDGPU_GEM_CREATE_VRAM_CONTIGUOUS) {
> +		(*bo)->placements[0].flags |= TTM_PL_FLAG_CONTIGUOUS;

That is a pretty clearly broken approach. (*bo)->placements[0].flags is 
just used temporary between the call to 
amdgpu_bo_placement_from_domain() and ttm_bo_validate().

So setting the TTM_PL_FLAG_CONTIGUOUS here is certainly not correct. Why 
is that necessary?

Regards,
Christian.

> +	} else {
> +		(*bo)->flags |= AMDGPU_GEM_CREATE_VRAM_CONTIGUOUS;
> +		amdgpu_bo_placement_from_domain(*bo, (*bo)->allowed_domains);
> +		for (i = 0; i < (*bo)->placement.num_placement; i++)
> +			(*bo)->placements[i].flags |= TTM_PL_FLAG_CONTIGUOUS;
> +		r = ttm_bo_validate(&(*bo)->tbo, &(*bo)->placement, &ctx);
> +		if (r)
> +			return r;
> +	}
>   
>   	return amdgpu_ttm_alloc_gart(&(*bo)->tbo);
>   }